Pages

▼

Important Bone Tumors

Author: Dr Ayush Goel

 Important Bone Tumors:

 1. Osteosarcoma: 
  • Age: 10-20 yrs (except when its secondary e.g. in Paget's disease in old age)
  • Metaphyseal
  • Sunray periosteal reaction
    • note: sunburst calcification on abdominal X-ray is seen in Pancreatic serous cystadenoma
  • Codman triangle 
    • note: codman tumor is chondroblastoma
  • Radioresistant
2. Ewing's sarcoma
  • Age: 10-20 yrs
  • laminated periosteal reaction: onion skin
  • location: diaphyseal
  • Radiosensitive
3. Giant cell tumor (GCT) = osteoclastoma
  • Epiphyseal
    • other epiphyseal lesions - Chondroblastoma, Geode
  • Soap bubble appearance
  • Metaepiphyseal: Seen after fusion of epiphysis (age 20-50 yrs)
4. Vertebral hemangioma
  • X-ray and Sagittal CT: Corduroy cloth appearance
  • Axial CT: Polka dot appearance
5. Adamantinoma
  • Mandible (Ameloblastoma): 3rd-5th decade
  • Tibial diaphysis: 10-20 yrs, typically anterior cortex
  • Pituitary (Both pituitary stalk and enamel arise from oral epithelium)
6. Above 60 years, multiple lytic lesions
  • Multiple myeloma 
    • Normal alkaline phosphatase, cold on bone scan
    • punched out lytic lesions
  • Metastases
    • Increased alkaline phosphatase, hot on bone scan i.e. high uptake
7. Metastases
  • Sclerotic/osteoblastic
    • Commonly from: Prostate and Breast (can have mixed)
    • Other: Stomach, Carcinoid
  • Lytic and expansile
    • Commonly from Kidney and Thyroid
8. Hyperparathyroidism
  • subperiosteal bone resorption
    • radial aspect of proximal and middle phalanges of the 2nd and 3rd fingers
    • lamina dura: floating teeth
  • Salt and pepper skull = pepper pot skull
  • Brown tumor
  • erosion of lateral end of clavical
  • rugger jersey spine (secondary hyperparathyroidism due to renal osteodystrophy)
    • note: picture frame vertebra is seen in Paget's disease of bone (also Cotton wool skull in Paget's)
    • note: sandwich vertebra is seen in osteopetrosis
9. Eosinophilic granuloma
  • children
  • beveled edges
  • vertebral plana
  • floating teeth (also seen with hyperparathyroidism)

1 comment:

Pulmonary aspergillosis


Pulmonary aspergillosis can present in 3 major forms:
  • Aspergilloma
    • fungal ball in an old tuberculous cavity
    • shows Monad sign (usually also called air crescent sign)
  • Allergic bronchopulmonary aspergillosis (ABPA)
    • central bronchiectasis
    • gloved finger appearance
    • fleeting opacities
  • Invasive aspergillosis
    • in immunocompromised
    • shows CT halo sign
      • Note: Reverse CT halo/Atol sign is seen in Cryptogenic organizing pneumonia/bronchiolitis obliterans organising pneumonia (COP/BOOP)
    • air crescent sign - it defines improvement/recovery in the underlying lesion with increased granulocyte activity (should not be confused with Monad sign which is also called air crescent sign as the air outlining the fungal ball is also in the shape of crescent) 

Author: Dr Ayush Goel
No comments:

Medical One Liners 421-430


421. For lung investigation - CT scan is best, except in Pancoast tumour/Superior sulcus tumour where MRI is investigation of choice to look for brachial plexus involvement.

422. Silhouette's sign or more correctly loss of silhouette sign:
  • Middle lobe pathology: obscures right heart border
  • Lower lobe pathology: obscures diaphragm
  • Lingular pathology: left heart border
  • Posterior segment of left upper lobe: aortic knuckle
  • Also see this MCQ: here
423. Lordotic chest X-ray view is used for:
  • Middle lobe examination (best view)
  • Lung apex pathology
  • Interlobar fissural effusion
424. Mammography:
  • screening in >40 yr females - once yearly
  • to detect DCIS - MRI is best (done in 2nd week of menstruation)
  • in young female, mammography is not useful as there is a lot of glandular tissue that makes the breast very dense
  • Most common sign of malignancy seen on mammogram: microcalcification
  • Popcorn calcification in breast: Fibroadenoma {Note: Popcorn calcification in lungs - pulmonary hamartoma, it also has fat in the lesion}
425. Radiation doses: 
  • Extremity X-ray = DEXA < Chest X-ray < Mammography < CT head < CT chest < CT Abdomen and pelvis < Coronary CT angiography < PET/CT
  • Barium studies have doses close to CT head, except Barium enema which has dose just less than CT chest.
426. HRCT Lung - uses bone algorithm for image reconstruction, useful for:
  • interstitial lung diseases and bronchiectasis
--> HRCT in Alveolar proteinosis: Crazy pavement appearance (see also: MCQ)
--> HRCT is also used in temporal bone imaging.
  • for Bony labyrinth: do CT
  • Membranous labyrinth: do MRI
427. All fractures are well visualized on CT except stress fracture which is best seen on MRI due to edema.

428. MRI uses free induction decay to receive signals.
Absolute contraindication:
  • Pacemaker
  • Metallic (ferromagnetic) implant/foreign body
429. Substances that are white/hyperintense on T1 Weighted MRI:
  • fat
  • subacute haemorrhage
  • posterior pituitary
  • melanoma and its metastases
430. CSF is white on T2 weighted image and dark on T1 weighted image. 



No comments:

X-ray photon interaction with matter


X-ray photon interaction with matter can occur in various forms:

  • Photoelectric effect {low energy photon (energy just greater than binding energy of electron) interacts with innermost shell electron}- MCQ
    • directly proportional to atomic number of matter
    • inversely proportional to cube of incident photon energy
    • maximum with tightly bound electrons (i.e. innermost shell - K)
  • Compton scattering/effect
    • is the cause of scatter radiation and thus increase radiation dose
    • does not depend on atomic number
    • inversely proportional to photon energy
  • Coherent scattering
  • Pair production (not important in diagnostic radiology)


Author: Dr Ayush Goel
D
No comments:

Stroke

Author: Dr Ayush Goel

 Stroke (cerebrovascular accident) is a neurological deficit that can occur due to:
  • ischemia (ischaemic stroke)
  • haemorrhage (haemorrhagic stroke)
    • lobar haemorrhage
    • hypertensive haemorrhage
Imaging

CT scan
First investigation to be undertaken is CT scan, to rule out haemorrhage. It is thus the investigation of choice for haemorrhagic stroke.

Axial Non contrast CT image showing left capsuloganglionic haemorrhage as hyperdense area
Image courtesy: Dr Ayush Goel
Hyperacute/early Ischaemic stroke is best evaluated on MRI (see below), however, there are subtle signs that may be present on CT to help make a diagnosis:

  • Hyperdense MCA sign: shows clot in MCA (earliest sign on CT)
  • Loss if Insular ribbon
  • Loss of grey-white matter differenciation
Red - loss of insular ribbon and grey-white matter differentiation; green - normal insular ribbon, blue - normal deep grey matter.
Image courtesy: Dr Ayush Goel

Later, even CT can demonstrate the infarcted area very well as wedge shaped hypodensity in the particular vascular territory.
Chronic infarct in left MCA terriotory
Image courtesy: Dr Ayush Goel
MRI
It is the investigation of choice for ischaemic stroke.
Diffusion weighted MR imaging is the earliest to detect ischaemic region as hyperintense on DWI and hypointense on ADC maps.
ADC (Red circle) and DWI (Blue circle)
Image courtesy: Dr Garima Goel




MedicoNotebook - Founder : DrShiviMudgal (Goel) , Co-Founder : DrAyushGoel
No comments:

Medical One Liners 411-420


411. Bulging fissure sign: Klebsiella pneumonia

412. Venous sinus thrombosis CT:
  • Non contrast - dense delta sign
  • Contrast CT - empty delta sign
413. Worst headache of life: Subarachnoid haemorrhage

414. Investigation of choice for
  • aneurysm - angiography
  • aortic aneurysm - CT scan as there may be intraluminal thrombus
  • aortic dissection - MRI
415. Basal exudates on CT seen in: Tuberculous meningitis and cryptococcal meningitis.

416. Contrast of X-ray image is inversely related to kVp.

417. Radiation intensity is inversely proportional to square of distance from the radiation.

418. Chest X-ray PA view is taken with film to focus distance of 180 cm. Chest AP view and other X-rays are taken at 100 cm.

419. Golden S sign: Right upper lobe collapse due to hilar mass.

420. Most common lung carcinoma with cavitation: Squamous cell carcinoma



MedicoNotebook - Founder : DrShiviMudgal (Goel) , Co-Founder : DrAyushGoel
No comments:

Myocardial perfusion and viability

Author:  Dr Ayush Goel

Myocardial perfusion and viability assessment is important for many reasons:
  • to diagnose, locate and grade the severity of coronary artery disease
  • to identify candidates who would benefit from re-vascularization
  • to evaluate response of re-vascularization
Terminology
Stunned myocardium
It refers to a state in which there is wall dysfunction but the perfusion (resting and stress) is normal.
Myocardial ischemia
It refers to a state in which there is decreased perfusion on stress but normal during rest (seen as reversible perfusion defect). These patients will significantly benefit with treatment.
Hibernating myocardium
In this the myocardium shows decreased perfusion on both stress and resting phase (seen as fixed defect) but the myocytes are viable and will benefit from revascularization.
Myocardial infarct
In this there is absent perfusion on both stress and resting phase (seen as fixed defect) and the myocytes are not viable. There will be no benefit from revascularization.

Imaging techniques

  • thallium-201 SPECT
    • excessive radiation dose (c.f. 99mTc-MIBI)
    • redistribution may occur
    • single injection for stress and resting phase
  • 99mTc-Sestamibi SPECT
    • less radiation dose
    • no redistribution
    • separate injections for stress and resting phase
  • FDG-PET (for viability)
    • based on the fact that myocardium utilizes glucose for metabolism when under effect of ischemia (hence the ischemic myocardium will show greater uptake than normal cells)
    • under normal circumstances, it utilizes fatty acids for energy
    • non-viable myocardium will not show any uptake
  • Cardiac MR perfusion imaging


This article was exported to Radiopaedia.org on 24th May 2015 by the author.

MedicoNotebook - Founder : DrShiviMudgal , Co-Founder : DrAyushGoel
No comments: